Some other things to consider...
How are you attaching the tubes to each other? Welding? Epoxy? Bolts
through? The stress distributes differently in each case.

How much bending can you tolerate? You can build a fairly tall, but
flexible, structure that flops around a lot, and doesn't put much load on
any one part of the system. You can also build a very stiff structure that
puts all the load at one place.

At 05:46 PM 11/7/2003 -0500, Jim White, K4OJ wrote:

FOR ME

I would step down the overlaps as you went yup - start with a longer
overlap say 1 foot and decrease it by and inch or two with each downsizing...

The cumulative mechanical needs of the tubing are less as you go up - at
the bottom all of the tubes are attached to the bottom one... the top
piece does NOT have anything "after it"

CAUTION NO ENGINEERING CREDENTIALS ONLY A LIFETIME OF EXPOSURE TO AMATEUR
RADIO

K4OJ

Macie, Gordon wrote:

I am building a 40 meter 4-square. I have decided to build it with aluminum
from Texas Towers. The bottom section will be 1.625 and reduce 1/8 per
section above that with the top peice being .875. How much do I need to
overlap or telescope into each section for mechanical strength ??.. I am
thinking 6 to 12 inches.
Blurb below from Texas Towers web site.
6063-T832 Drawn Aluminum Tubing Typical yield strength of 40,000 psi. The
chart shows all available
telescoping sizes which are specifically designed to fit together precisely,
making antenna construction easy, while offering professional results.
TowerTalk@contesting.com